Over 485,000 persons undergo coronary artery bypass grafting (CAGB) each year in the United States. While CAGB is effective for mitigating angina and other cardiac symptoms, 30-79 percent of patients have been reported to have postoperative cognitive decline. The cause or this decline is uncertain; the role of the specific features of cardiopulmonary bypass (bypass pump, aortic manipulation and hypothermia) versus the effects of prolonged general anesthesia and other surgical factors has not been resolved. Similarly the possible roles of Alzheimer's Disease (AD) or depression remain uncertain. This controlled prospective study will compare cognitive outcomes in 3 groups of patients from a pool of patients with coronary artery disease: patients undergoing CABG; patients undergoing minimally invasive direct coronary bypass (MIDCAB), a procedure performed on the beating heart without the bypass pump, aortic manipulation, or hypothermia; and non-surgical patients from the cardiac clinic. Patients will be evaluated with neuropsychological tests and measures of depression preoperatively, at 3 months and at 1 year. Those with progressive declines will be evaluate for possible AD. Specific Aim 1 will compare the incidence of cognitive decline in the three groups, to determine if decline is specific to CABG. Aim 2 will assess the effects of depression and/or AD on cognitive decline. Aim 3 will identify variables, including surgical procedure, associated with any observed declines. The long term objective of this proposal is to determine the role of cardiopulmonary bypass surgery in postoperative decline after CABG with the ultimate purpose of proposing interventions to overcome these adverse effects. Such information is essential for the design of interventions to prevent these postoperative effects.